1. Field of the Invention
The present invention relates to a dispenser and a dispensing device and, more particularly, to a dispenser and a dispensing device, which are enabled to detect an internal pressure to be produced in a syringe of the dispenser, precisely and promptly by directly connecting an air intake port of a pressure sensor for detecting the pressure in the syringe, to a through hole formed through the syringe inside.
2. Related Art
As shown in FIG. 10, a dispenser 131 in the related art is internally provided with a stepping motor 152 to be activated when fed with a driving pulse signal, so that it sucks and discharges a liquid from a pipette nozzle 132. The dispenser 131 is substantially constructed to include: the pipette nozzle 132; a disposable tip 133 retained in removable engagement on the leading end of the pipette nozzle 132; a pressure sensor 134 arranged in a pressure detecting passage 180 for detecting the pressure in the pipette nozzle 132; a cylinder 135; a cylinder rod 151 made slidable back and forth in the cylinder 135; and the stepping motor 152 for moving the cylinder rod 151 back and forth.
Above the cylinder rod 151, there is arranged a screw bolt 141 which is threaded in its outer circumference. This screw bolt 141 is screwed in a screw nut 136, which is fixed on a frame 146 of the dispenser. A timing belt 139 trained between a pulley 140 mounted on the screw bolt 141 and the spindle of the stepping motor 152.
On the other hand, the exit end portion at the lower end of the cylinder 135 and the pipette nozzle 132 are connected to communicate with each other via an air vent passage 181. The pipette nozzle 132 is biased outward with respect to the frame 146 of the dispenser 131 by a spring 145.
In the dispenser 131, moreover, there are arranged: a lower limit sensor 138 for detecting the lower limit of the cylinder rod 151; an upper limit sensor 143 for detecting the upper limit of the cylinder rod 151; and a grounding sensor 137 for detecting the grounding of the pipette nozzle 132.
The dispensing action of the dispenser 131 thus constructed is controlled by a separate control unit for the dispenser.
In the controls, specifically, the control unit measures the change in the internal pressure of the pressure sensor 134 while a suction is continued by lowering the disposable tip 133 mounted on the pipette nozzle 132 of the dispenser 131, to thereby detect either the arrival of the tip at the liquid level or the clogging of the tip with respect to a preset threshold value. When a predetermined suction is detected, the control unit stops the suction and raises the dispenser 131.
In the dispenser thus far described, however, the pressure sensor for detecting the internal pressure of the pipette nozzle is located at a position remote from the nozzle. This positioning raises a problem that the pressure in the pipette nozzle cannot be precisely detected.